<!--
 * @Description: https://gitee.com/bingofree/keras_mall.git
 * @Author: Created by nzb@yeah.net qq:9679489
 * @Date: 2019-03-22 23:03:14
-->
<template>
    <el-color-picker :size="size" class="theme-picker" popper-class="theme-picker-dropdown" v-model="theme">
    </el-color-picker>
</template>

<script>
const version = require('element-ui/package.json').version // element-ui version from node_modules
const ORIGINAL_THEME = '#409EFF' // default color
export default {
    name: 'ThemePicker',
    props: {
        default: { // 初始化主题，可由外部传入
            type: String,
            default: null
        },
        size: { // 初始化主题，可由外部传入
            type: String,
            default: 'small'
        }
    },
    data () {
        return {
            chalk: '', // content of theme-chalk css
            theme: ORIGINAL_THEME,
            showSuccess: true // 是否弹出换肤成功消息
        }
    },
    mounted () {
        if (this.default !== null) {
            this.theme = this.default
            this.$emit('onThemeChange', this.theme)
            this.showSuccess = false
        }
    },
    watch: {
        // eslint-disable-next-line padded-blocks
        theme (val, oldVal) {

            if (typeof val !== 'string') return
            const themeCluster = this.getThemeCluster(val.replace('#', ''))
            const originalCluster = this.getThemeCluster(oldVal.replace('#', ''))
            // console.log(themeCluster, originalCluster)
            const getHandler = (variable, id) => {
                return () => {
                    const originalCluster = this.getThemeCluster(ORIGINAL_THEME.replace('#', ''))
                    const newStyle = this.updateStyle(this[variable], originalCluster, themeCluster)

                    let styleTag = document.getElementById(id)
                    if (!styleTag) {
                        styleTag = document.createElement('style')
                        styleTag.setAttribute('id', id)
                        document.head.appendChild(styleTag)
                    }
                    styleTag.innerText = newStyle
                }
            }

            const chalkHandler = getHandler('chalk', 'chalk-style')

            if (!this.chalk) {
                const url = `https://unpkg.com/element-ui@${version}/lib/theme-chalk/index.css`
                this.getCSSString(url, chalkHandler, 'chalk')
            } else {
                chalkHandler()
            }

            // eslint-disable-next-line prefer-const
            let styles = [].slice.call(document.querySelectorAll('style'))
                .filter(style => {
                    const text = style.innerText
                    return new RegExp(oldVal, 'i').test(text) && !/Chalk Variables/.test(text)
                })
            styles.forEach(style => {
                const { innerText } = style
                if (typeof innerText !== 'string') return
                style.innerText = this.updateStyle(innerText, originalCluster, themeCluster)
            })

            // 响应外部操作
            this.$emit('onThemeChange', val)
            if (this.showSuccess) {
                this.$notify({
                    title: '成功',
                    message: '换肤成功',
                    type: 'success'
                })
            } else {
                this.showSuccess = true
            }
        }
    },
    methods: {
        updateStyle (style, oldCluster, newCluster) {
            let newStyle = style
            oldCluster.forEach((color, index) => {
                newStyle = newStyle.replace(new RegExp(color, 'ig'), newCluster[index])
            })
            return newStyle
        },

        getCSSString (url, callback, variable) {
            const xhr = new XMLHttpRequest()
            xhr.onreadystatechange = () => {
                if (xhr.readyState === 4 && xhr.status === 200) {
                    this[variable] = xhr.responseText.replace(/@font-face{[^}]+}/, '')
                    callback()
                }
            }
            xhr.open('GET', url)
            xhr.send()
        },

        getThemeCluster (theme) {
            const tintColor = (color, tint) => {
                let red = parseInt(color.slice(0, 2), 16)
                let green = parseInt(color.slice(2, 4), 16)
                let blue = parseInt(color.slice(4, 6), 16)

                if (tint === 0) { // when primary color is in its rgb space
                    return [red, green, blue].join(',')
                } else {
                    red += Math.round(tint * (255 - red))
                    green += Math.round(tint * (255 - green))
                    blue += Math.round(tint * (255 - blue))

                    red = red.toString(16)
                    green = green.toString(16)
                    blue = blue.toString(16)

                    return `#${red}${green}${blue}`
                }
            }

            const shadeColor = (color, shade) => {
                let red = parseInt(color.slice(0, 2), 16)
                let green = parseInt(color.slice(2, 4), 16)
                let blue = parseInt(color.slice(4, 6), 16)

                red = Math.round((1 - shade) * red)
                green = Math.round((1 - shade) * green)
                blue = Math.round((1 - shade) * blue)

                red = red.toString(16)
                green = green.toString(16)
                blue = blue.toString(16)

                return `#${red}${green}${blue}`
            }

            // eslint-disable-next-line prefer-const
            let clusters = [theme]
            for (let i = 0; i <= 9; i++) {
                clusters.push(tintColor(theme, Number((i / 10).toFixed(2))))
            }
            clusters.push(shadeColor(theme, 0.1))
            return clusters
        }
    }
}
</script>

<style lang="scss">
.theme-picker .el-color-picker__trigger {
    vertical-align: middle;
}

.theme-picker-dropdown .el-color-dropdown__link-btn {
    display: none;
}
</style>
